题目：Analysis of Turbulent Flows by Simultaneous Fluorescent and Mie-Scattering PIV
时间：2025年6月18日 9:30-11:00
地点：williamhill威廉希尔官网 振华会议室
邀请人：彭迪 教授（叶轮机械研究所）
报告人简介
Christian J. Kähler 博士是德国慕尼黑联邦国防军大学（Universität der Bundeswehr München）教授，现任该校流体力学与空气动力学研究所所长。他目前担任国际实验流体力学领域期刊《Experiments in Fluids》主编，并入选德国洪堡基金会评选委员会。他曾担任2018年国际实验流体力学大会及2019年国际粒子图像测速研讨会等国际会议主席。Kahler教授的研究兴趣广泛，涵盖光学流场诊断技术的发展与应用，以及亚音速、跨音速、超音速条件下微流体与湍流中的复杂流动机理。其合著的第三版《Particlelmage Velocimetry》(粒子图像测速技术)专著已被引用超过8000次。
报告摘要
Many flows have a multi-constituent nature, where understanding the transfer of mass and momentum between different parts of the flow is key. While experiments in liquid media have long used flow tagging techniques such as dye injection to isolate parts of the flow, analogous methods that do not compromise full-field velocimetry in gas flows are highly impractical. The recent introduction of a solution of Pyrromethene 567 (P567) in Di-Ethyl-Hexyl-Sebacate (DEHS) to produce a seeding fluid capable of fluorescent emission in addition to Mie scattering promises to address this need. By locally seeding a secondary flow of interest with the modified DEHS, the fluorescent signal can be used for tagging; global seeding of main flow with standard DEHS, which only produces Mie scattering of incident laser light, is used to obtain full-field velocimetry with established PIV techniques. Performing morphological image processing and intensity-based thresholding on the fluorescent particle images yields a continuum representation of the secondary flow. This can then be combined with velocimetric information from PIV to conduct quantitative zonal analyses. This technique has been applied to the flow behind an active synthetic-jet turbulence grid and a turbulent boundary layer (TBL). With the new zonal decomposition capabilities offered, data relating to the intermittency of the flows, statistical structure of the phenomena, turbulent/non-turbulent interface (TNTI) and entrainment and detrainment can be extracted.
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